The scant hair mutant mouse(locus symbol:snthr1Bao) is a recessive mutation that originated in an ethylnitrosourea chemical carcinogenesis study using the DBA/2J inbred strain.The gene responsible for the mutation was previously determined to be phospholipase C,delta 1(Plcd1;mutant allele symbol Plcd1snthr1Bao).To map the modifiers of Plcd1,an intercross(DBA/2J-snthr1Bao/snthr1Bao × C57BL/6J+/+) was conducted.The F2 mutant progeny exhibited a variety of alopecia phenotypes;all F2 mutants(n=507) were classified into 3 groups(mild,moderate,and severe alopecia) and genotyped based on 96 microsatellites.A major QTL was identified on mouse chromosome(mChr) 15 at 12 cM with an LOD score greater than 7(P < 0.0001).Three minor QTLs were detected on mChr 2,5,and 7 at 40,84 and 48 cM,respectively.The QTLs on mChr 7 and 15 were associated with minor alopecia while the QTLs on mChr 2 and 5 were associated with moderate to severe alopecia.No antagonistic or synergistic effects among or between the 4 QTLs were found.Integrating the functions of the 4 potential regulatory QTLs and mutant Plcd1snthr1Bao,we found that these QTLs might contribute to variations of scant hair severity by altering the Ca2+ signal pathways in mouse skin.
